TCA and Oxidative Phosphorylation

Question 1

What is the net yield of the TCA cycle?

Answer 1

2 CO2 (Released in breath) + 3 NADH (To ox. phos.) + 1 FADH2 (To ox. phos.) + 3 H+

Also GDP

Question 2

Is any ATP made or oxygen used in the TCA cycle?

Answer 2

No

Question 3

Where does the TCA cycle occur?

Answer 3

Mitochondrial matrix

Question 4

What are the four major substrates for the TCA cycle?

Answer 4

Acetyl CoA (From pyruvate, fatty acid breakdown, ketone bodies, or ketogenic AAs), other carbon sources (Alpha-ketoglutarate or proprionate), oxidized cofactors (NAD+, FAD), and GDP/Pi

Question 5

What does citrate synthase oversee?

Answer 5

The conversion of acetyl CoA and water to citrate and CoASH

Question 6

What does isocitrate dehydrogenase oversee?

Answer 6

The conversion of isocitrate and NAD+ to alpha-ketoglutarate, NADH, and CO2

Question 7

What does alpha-ketoglutarate dehydrogenase oversee?

Answer 7

The conversion of alpha-ketoglutarate, CoASH, and NAD+ to succinyl CoA, NADH, and CO2

Question 8

What can upregulate the TCA cycle?

Answer 8

Exercise, low temperatures, disease

Question 9

What can downregulate the TCA cycle?

Answer 9

Rest, hybernation, recovery

Question 10

What body signals are used to regulate the TCA cycle?

Answer 10

Endocrine system, CNS, para/sympathetic stimulation, ATP/ADP ratio, NAD+/NADH ratio

Question 11

What process ensures that pyruvate will not participate in gluconeogenesis?

Answer 11

Oxidative decarboxylation of pyruvate to form Acetyl CoA via the pyruvate dehydrogenase complex

Question 12

Once pyruvate is converted to Acetyl CoA, what two things can happen?

Answer 12

Oxydation to CO2 via the TCA cycle to generate energy or incorporation into lipid

Question 13

How does insulin increase the rate of activity of the pyruvate dehydrogenase complex?

Answer 13

Dephosphorylates pyruvate dehydrogenase, therefore accelerates conversion of pyruvate to Acetyl CoA

Question 14

How is citrate synthase regulated?

Answer 14

Allosterically inhibited by ATP

Question 15

How is isocitrate dehydrogenase regulated?

Answer 15

Allosterically stimulated by ADP

Question 16

How is alpha-ketoglutarate dehydrogenase regulated?

Answer 16

Inhibited by high energy charges

Question 17

What is the ATP equivalent of NADH?

Answer 17

3 ATP = 1 NADH

Question 18

What is the ATP equivalent of FADH2?

Answer 18

2 ATP = 1 FADH2

Question 19

What is the ATP equivalent of GTP?

Answer 19

1 ATP = 1 GTP

Question 20

Where does oxidative phosphorylation occur?

Answer 20

The inner mitochondrial membrane

Question 21

What are the two components of oxidative phosphorylation?

Answer 21

Electron transport chain (Creates proton gradient) and phosphorylation of ADP to create ATP

Question 22

What are the four major functions of oxidative phosphorylation?

Answer 22

Production of ATP, oxidation of reduced cofactors, restoration of reduced cofactors, water production

Question 23

What does the electron transport chain need to function?

Answer 23

Protons (From environment), reduced cofactors (From TCA, beta-oxidation, glycolysis), oxygen (From circulating hemoglobin or myglobin)

Question 24

What does ATP synthase need to function?

Answer 24

ADP, phosphate (Inside the mito.), protons

Question 25

What are the products of the electron transport chain?

Answer 25

Water, oxidized cofactors

Question 26

What is the product of ATP synthase?

Answer 26

ATP

Question 27

Name the complexes of the electron transport chain and their functions.

Answer 27

Complex I (Oxidizes NADH, passes electron to ubiquinone), Complex II (Oxidizes FADH2, passes electron to ubiquinone), ubiquinone (Also CoQ 10, passes electrons to the next unit), Complex III (Oxidizes ubiquinone, reduces cytochrome C (Takes electron from ubiq. and gives to cyto. c)), cytochrome C (Passes electrons to next unit), Complex IV (Reduces/passes electrons to oxygen)

Question 28

What is characteristic of the Fo unit of ATP synthase?

Answer 28

Transmembrane proton channel, inhibited by oligomycin

Question 29

What is characteristic of the F1 unit of ATP synthase?

Answer 29

3 alpha and 3 beta subunits organized around a central gamma unit, proton passes into alpha/beta subunits, ADP + Pi bind to beta subunits, and rotation of the unit produces ATP

Question 30

What effect do muscle movement, CNS (To maintain Na+/K+ pump), and growth/repair have on oxidative phosphorylation?

Answer 30

Increases rate

Question 31

When does oxidative phosphorylation reduce its activity?

Answer 31

Hibernation/sleeping

Question 32

Which two situations affect oxidative phosphorylation?

Answer 32

Breathing (Need oxygen at end of electron transport chain to accept final electron) and ADP availability (Need ADP and Pi in order for it to occur)

Question 33

How is oxidative phosphorylation interrupted?

Answer 33

Uncouplers (Which allow protons to leak back through the membrane for heat production in brown fat), rotenone (Insecticide that inhibits complex I), antimycin (Antibiotic that inhibits complex III), cyanide/carbon monoxide (Inhibit complex IV), oligomycin (Inhibits proton channel of Fo subunit), Bongkrekic acid/atractyloside (Prevents ATP from exiting cell and ADP from entering)